Automatic slack adjuster for brakes



Dec.'8, 1931. B. H. BRowALL AUTOMATIC SLACK ADJUSTER FOR BRAKES Filed May 16, 1929 3 Sheets-Sheet l l QQQQQM ff @il DSG 8, 1931- B. H. BRowALL.

AUTOMATIC SLACK ADJUSTER FOR BRAKES Filed May 16, 1929 3 Sheets-Sheet 2 Z7 www Dec. 8, 1931.

B. H. BRQWALL AUTOMATIC SLACK ADJU'STER FOR BRAKES Filed May 16, 1929 3 Sheets-Sheet 5 Patented Dec. 8, 1931 uni-ren lerares PATENT oFFi-,c-E

BERT HENRY- BnowALn, or Marano, SWEDEN, Assmann 'ro s'vmzsim Ax'rinnonaem nnom'snm'nnaron, or' Marmo, SWEDEN', A .CORPORATION 0F SWEDEN Ummm-*1e smcx ADJ-asma ron lamas Application :ned lay '16 1929,. aerialA no. 363,492, and in Germany May 21, 192s.

The present` invention refers to an im- Y provemen-t inwautomatic slack adjnsters for brakes` on railway cars-and the like, and more specitically to a paratus of this kind, in

L4;y which the infteristance between the brake shoes and the wheels. is. controlled by means of a: spindle or rod which, at the application of the brakes,I is displaceable the direction of its'lengthA by means4 of a driving device m acting in one direction only, the influence of such one-way d rivi'` Adevice on the spindle or rod ceasin whent e stress, arising in the brake rigging during braking, hasreached a certain. predetermined value'.

m l In order that the inlluence ofthe one-way driving device oir the spindle or rod will cease atthe predetermined moment, it has previously been proposed to use a screw spindle, the displacement of' which is ob.-

tained by the turning of the same, and to provide the slack adjnster, besides the oneway driving device mentioned above., with a. releasable clutchby ineanso which the adjusting power is transmitted to the adjuster 'jas spindle, whereby the release of the chitch is performed by means .of kthe stress arising in the brake rigging when braking, the one-way driving device .being then permanently in engagement. y

An arrangement of this kind involves, y however, unnecessary complications: in constructional respectsf, .and kthe main object of the invention, is lto eliminate such complica.- tions. The principle of the invention to be 'p35 found therein is. that the apparatus, without the assistance of any releasable clutch, is put out of,k action `by means of the stress. arising when braking, whereby such stress is. utilized ior disengagementof the ene-way driving device itself.

A similar arrangement may also be used in; slack adjnsters` provided with an adjusting rod which isfdire'etly kdisplaceable inl. its

45 difrectioi'i of length Without turn-ingv of the same, as will be farther disclosed in the following. y The invention is illustrated in the accom- Y panyingdrawings, in which rg0 Fig. 1 shows an embodiment. of the invention, in. which the one-way driving device consists of al pawl and ratchet mechanism.

Figs. 2 and 2a show another embodiment of the invention wherein the driving device is Carried out in the form of a one-way friction pawl and disc mechanism; the pa'wl being shown in operative and inoperative position, respectively, in these two views. y

Fig. 3 shows a third embodiment provided' with a driving device consisting of two coacting ratchet wheels forming a one-way clutch.

Fig. 4 shows a fourth embodiment of the invention, according to which the same principle is applied to a slack adjuster provided with a directly displaccable rod instead of a turnabl'e spindle, all four figures being views in longitudinal section.

' Figs. 5 and 6 show the mounting of the apparatus according to Figs. 1 and 4, respectively. l l

In all of the figures the same reference characters indicate corresponding parts.

According toy Figs. lf3 the reference numeralV 1 represents the adjuster rod or spindle and 2 the driven member of the one-way driving device rigidly connected with said spindle. At one end, the spindle 1 is provided with a head 3 preferably mountedy within a cavity kin a housing 4 forming a part of the connection e e by ymeansof which the spindle or rod incluv ing the slack adjuster is connect- 'ed with the brake rigging. Between the head 3' and an' abutment within the housing 4 is interposed a rather strong spring 5 acting in op.- position to the stress arising in the apparatus when braking. On the housing, and al'soon the spindle 1, is freely rotatably mounted' a protection sleeve 6y surrounding the mechanism and provided with a crank member(y by means of which the sleeve 6 may be turned by influence from an actuating member connected with a movable part of the brake rigging, so that the sleeve is turned a certain angle in one direction when applying the brakes, and back again when releasing the same.

The parts of the apparatus described above are to be considered as previously known and form themselves no part of the invention.

In the embodiment according to Fig'. 1' the of the ratchet Wheel is effected When rotating-- the sleeve 6 in one direction only, the rota! tion of the sleeve in the opposite direction be-fi;

ing a dead or idle motion. The paWl 8 coacts With a lever *9 which"V is hingedly connected Withthe interior of the sleeve Gand provided with a transverse abutmentpin' 10 extending from the end *of lever 9 and positioned behind the pawl. The lever 9 isalso provided with aV cam surface at 11rk contacting with airingsliaped 'collar 12 on the'spindle 1, and one or more springs 8ai maybe arranged in a lsuitable manner so 'as normally` to keep the pfaivl 8 en-` gaged withth-eratchetwheel 2. L

'Y Under the conditie 1 that theinterdistance between the brake shoes and the ivheelsistoo large, the performance of a braking actiony Will at first causea turning increment of they sleeve', andsaid sleeve,by the intermediary of thep'awl and ratchet mechanism, transmits theturning movement tothe adjuster rod or spindle'l,until a-certain amount of stress arises in the brakefrigging such as will overcome the springV 5 andcompress the same, so that thespindle v1. and the partsaiiixed thereto'ivill beA longitudinally displaced inrelatio'n to the Vother parts of the apparatus. larY 12, by means, of the cam surface 11, Will then press back the leverr 9, yand the V pin 10 thereon Will release thep'aWl 8 Vfrom engagement with the ratchet Wheel 2, whereupon the continued turninginovement of the sleeve 6 Willlhave'no further influence on the adjuster mechanism., 1 f y Y .l lIn the; embodimentaccording to'Fig. -2 cor-l responding reference numerals arefused on similar parte, as aforesaid, anditheraction of this 7 apparatusrwill be understood Without furtherl description Orff eXplanation.` 1 The only diiferenceis that forY the ratchet lwheel 2 there is substituted pacsmooth, flange 2a coact-v ing Withoneorinore friction pawls lgpivot allyk mountedon iiXed'f'l-ugs Within thefsleeve t3, fsu'clh friction; payvlsfbeing each :provided W'ithanfecfcentricfxvl king` -surface for ccacf tion with the'flallg'2.` Alsoin this casetlie i paivl 'or gpa'ivls`-13 mayfbe acted upon'by one or mo'rel'spr-ings (not shown) Av'for ,keeping them-permanently in contact with the said flange.v .i

The manner of actionof this embodiment is the saineas `described above,.and Whenthe predetermined amount' of stress arises When braking, theV flange 2a .will ,be longitudinally displaced .inf relation: to the pawl or pawls 13, so'that theworking'surface of the latter.V

Wheel 2b, ,and` provided fWith teeth inclined in one direction only. In this instance the i driving member-of` said device consists of another ratchet Wheel 111 substantially of the kind-fas thewheel- 2l.Av ThefWheel 14 is freelywrotatable around the spindle 1 and coupledY thefsleeve fby means'adapted for inducingr saidivheel to take part 'in the, rotation ofthe sleevcfbut"permitting it to be aida-ilyl displaced in relation thereto,so as to permit the ratchetv teeth to slide over each other at the baclr'ivard rotation of the Wheel 141e.' According toftliejembodiment shown, said last-'mentioned'means' consists of lugs 1:5 extending radially fromfthe' Wheel 14 into correspondinggrooves providedv in the innersurface the'v'slejeve v6 and extending substantially in vthedirectionofl length'of the latter. Theendsoflthegrooves 16 `nearest to the ratchet Wheel?,b form abutment surfacesfl limitin'gfithe displacement ofthe ratchetivheelzlll towards theleft in the draw ing, the limit being reached when the Wheels are fully in lengagement'with*eachother and corresponds to '5a :release v position of the brakes. j

'The manner of action ofthis embodiment is substantiallythe saine ras described above,

and vwhen asufiicient stress'is reached 'during braking the Wheel 2`Will be pulled cutof cngagenientv ivith the Wheel 14, Which latter, by means of' theabutments 17, is y'prevented from following lthe former' although acted.Vv upon by 'an engagement spring 18. V vrAtthe turning,` `movementofthe sleeve 6` in the op-k posite direction (when releasing;v the brakes), the teeth on the't'ivo Wheels `will slide back Wardlyf'on"v eachother y.Without any4 rotating movement transmitted vfrom the Wheel tothe Wheel-2r In ftheA embodiment according 'to '.Fig." il, the adjusterrodn'ly itself toothed, and Without beingturned 7it n'raybeU4 longitudinally displacedbyineans/ ofa pa'Wl 26 mounted pivotally 'on a-'lever '191the :free lend'of which is provided with a Vcam member 20. TheV lever 19 is pivotally ymounted in-avhousing` 421 surrounding' the; toothed rfroid Y, 1111 and provided with a :lockingV paWl`-221` fWhi'ch also engages saidrod.v :Betweenan abutment 23 providefil on a tubular member 211,-surrounding,` the rod 1L and a corresponding abutment 25A on' the housing v21 isrinterposedan expansionV spring 5, anda part connected with the tube 24,'for

instance thel abuftinent', forms" a carni sury face for coactionvviththe cam member20 in the housing 21. Then a suiiicient stress has grown up in the brake rigging, the spring will be compressed, and the abutment 23 moves to the right in the drawing, whereby the cam surface on the same acts lupon the cam member so as to tilt the lever 19 and to raise the pawl 26 out of engagement with the toothed rod la. The braking stress is then transmitted from the tube 24 to the rod member la by the intermediary of the abutments 27 and 25, the housing 2l and the pawl 22.

As to Figs. 5 and 6, these igures, as already stated, show the mounting of the apparatus in connection with Figs. l and 4, respectively. Thus, in Fig. 5, a indicates the brake cylinder and b the piston rod; c is the piston rod brake lever and d the slack adjuster, which latter is to be actuated by the crank 7. The piston rod head bolt e carries a bell-crank lever, one arm f of which, by means of a link g, connected with a iXed point on the car frame, while the other arm 7L of the bell-crank lever is connected by means of a link 1I with the crank member 7. New, when the piston rod b moves to the left during braking, the bell-crank lever f-L 'will turn about the bolt e, and by means of the link z', it will cause a tilting movement in the direction of the crank member 7; and when the pistonrod moves back again, in a corresponding manner the crank member 7 will be tilted in the opposite direction.

In Fig. 6, the same reference characters are used on corresponding parts of construction, and the figure shows the arrangement in connection with the embodiment of the apparatus shown in Fig. 4. The slack adjuster is indicated at (Z and is provided with the pawl 26, as described. The outer end of said pawl is connected by means of a link /c with a bell-crank lover m which is also connected with the link z'. When the piston rod moves to the left during braking, the bellcrank lever f-t is turned in the same manner as described above, and then it turns the bellcrank lever m, and the latter tilts the pawl 26 around its pivot in a counter-clockwise direction. lVhen the brake is released, the pawl will naturally be tilted a corresponding angle in the opposite direction, and such movements of the pawl perform the adjustment of the slack in the manner described.

`What I claim and desire to secure by Letters Patent is l. An automatic slack adjuster for brakes on railway cars and the like, comprising a one-way driving device, an adjuster rod associated therewith and displaceable in its direction of length, spring means counteracting such displacement when the stress arising in the brake rigging during braking overcomes the resistance of said spring means, characterized in that the driving and driven members of the driving device, are releasably connected with each other in such a manner that they are disengaged when the stress arising in the brake rigging during braking exceeds the value at which the longitudinal displacement of the adjuster rod takes place.

2. An automatic slack adjuster for brakes on railway cars and the like, comprising a movable adjuster rod, a one-way driving device for effecting the adjusting movement of said rod, spring means acting upon said rod in counter-action to the stress arising in the same during braking, means for permitting longitudinal displacement oi the rod when the braking stress overcomes said spring means, a releasable connection between the driving and driven members of the driving device, and means for releasinfr such connection when the stress arising in the brake rigging during braking exceeds the value at which the longitudinal displacement of the adjuster rod takes place against the counteraction of the spring means.

8. An automatic slack adjuster for brakes 100 on railway cars and the like, comprising a movable adjuster spindle rotatable to effect its adjusting movement, one-way driving device 'or turning said spindle, spring means acting upon the adjuster spindle in counteraction to the stress arising in the same during braking, means for permitting longitudinal displacement of the spindle when the braking stress overcomes said spring means, a releasable connection between the driving and driven members of the driving device, and means for releasing such connection when the stress arising in the brake rigging during braking exceeds the value at which the longitudinal displacement of the adjuster spindle takes place against the counteraction of the spring means.

In testimony whereof I have signed my name to this specification.

BERT HENRY BROVVALL. 120 

